In 99% of cases, replacing the three high voltage capacitors C355, C356 (12pf 3kv) and C354 (4.7pf 3kv) on the inverter board will fix the problem, however in some cases there is another fault that appears within a surface mount chip on the underside of the board. This fix will sort most TV's, but be aware of the possible other fault.
Main Symptom of this fault:
The TV appears to be working ok, but the picture goes off after a few seconds. Sound is still working and the TV responds to remote control as normal. The usual time that the screen stays on for is about 2 seconds, then it goes off. Actually, the picture is still there if you look at the right angle in the right light, but due to a fault on the inverter board the backlights have gone out making the screen very dark.
Here's how to fix it:
Lay the TV face down on a towel (to protect screen) on your bench with the stand hanging off the edge. Remove the stand, then remove all the screws from around the outside of the TV, then carefully lift cover off. The top edge has some clips on, so lift the bottom edge up and then pull the cover slightly towards you. it should come off reasonably easily without the need to force it.
Once the cover is removed you should see the Vestel 17IPS01-2 power/inverter board on the left hand side. Take a photo at this point, or draw a basic diagram of where all the wires plug in. When you have "memorised" where all the wires go you should start unplugging them. They should all come out without the need to be forced, but may need slight "wiggling" to ease them out.
Next, Unscrew the four screws holding the board in place and lift off. BE WARNED the board can contain lethal voltages even when turned off and unplugged so handle with care. If you are not sure about doing it, pay someone to do it for you!
Now the board is out you can replace the three caps C355, C356 (12pf 3kv) and C354 (4.7pf 3kv). The old capacitors when tested after removal, may read as good on a capacitor tester, but they do not work in the TV because under load they are breaking down. All three should be replaced together to ensure a proper repair. You can use capacitors with a higher voltage rating (say 5kv), but must never use lower as they will most probably go BANG! The 4.7pf cap can be replaced with 5pf 3kv and it will be fine.
Ok, now the caps have been replaced, you can put it all back together. Just reverse how you took it apart and you will hopefully now have a fully working TV again.
Good Luck! -Norm.